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* [PATCH AUTOSEL 4.4 1/7] spi: qup: call spi_qup_pm_resume_runtime before suspending
@ 2020-03-16  2:35 Sasha Levin
  2020-03-16  2:35 ` [PATCH AUTOSEL 4.4 4/7] spi/zynqmp: remove entry that causes a cs glitch Sasha Levin
  0 siblings, 1 reply; 2+ messages in thread
From: Sasha Levin @ 2020-03-16  2:35 UTC (permalink / raw)
  To: linux-kernel, stable
  Cc: Yuji Sasaki, Vinod Koul, Mark Brown, Sasha Levin, linux-arm-msm,
	linux-spi

From: Yuji Sasaki <sasakiy@chromium.org>

[ Upstream commit 136b5cd2e2f97581ae560cff0db2a3b5369112da ]

spi_qup_suspend() will cause synchronous external abort when
runtime suspend is enabled and applied, as it tries to
access SPI controller register while clock is already disabled
in spi_qup_pm_suspend_runtime().

Signed-off-by: Yuji sasaki <sasakiy@chromium.org>
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Link: https://lore.kernel.org/r/20200214074340.2286170-1-vkoul@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/spi/spi-qup.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/spi/spi-qup.c b/drivers/spi/spi-qup.c
index 810a7fae34798..2487a91c4cfdb 100644
--- a/drivers/spi/spi-qup.c
+++ b/drivers/spi/spi-qup.c
@@ -961,6 +961,11 @@ static int spi_qup_suspend(struct device *device)
 	struct spi_qup *controller = spi_master_get_devdata(master);
 	int ret;
 
+	if (pm_runtime_suspended(device)) {
+		ret = spi_qup_pm_resume_runtime(device);
+		if (ret)
+			return ret;
+	}
 	ret = spi_master_suspend(master);
 	if (ret)
 		return ret;
-- 
2.20.1

^ permalink raw reply	[flat|nested] 2+ messages in thread

* [PATCH AUTOSEL 4.4 4/7] spi/zynqmp: remove entry that causes a cs glitch
  2020-03-16  2:35 [PATCH AUTOSEL 4.4 1/7] spi: qup: call spi_qup_pm_resume_runtime before suspending Sasha Levin
@ 2020-03-16  2:35 ` Sasha Levin
  0 siblings, 0 replies; 2+ messages in thread
From: Sasha Levin @ 2020-03-16  2:35 UTC (permalink / raw)
  To: linux-kernel, stable
  Cc: Thommy Jakobsson, Naga Sureshkumar Relli, Mark Brown,
	Sasha Levin, linux-spi, linux-arm-kernel

From: Thommy Jakobsson <thommyj@gmail.com>

[ Upstream commit 5dd8304981ecffa77bb72b1c57c4be5dfe6cfae9 ]

In the public interface for chipselect, there is always an entry
commented as "Dummy generic FIFO entry" pushed down to the fifo right
after the activate/deactivate command. The dummy entry is 0x0,
irregardless if the intention was to activate or deactive the cs. This
causes the cs line to glitch rather than beeing activated in the case
when there was an activate command.

This has been observed on oscilloscope, and have caused problems for at
least one specific flash device type connected to the qspi port. After
the change the glitch is gone and cs goes active when intended.

The reason why this worked before (except for the glitch) was because
when sending the actual data, the CS bits are once again set. Since
most flashes uses mode 0, there is always a half clk period anyway for
cs to clk active setup time. If someone would rely on timing from a
chip_select call to a transfer_one, it would fail though.

It is unknown why the dummy entry was there in the first place, git log
seems to be of no help in this case. The reference manual gives no
indication of the necessity of this. In fact the lower 8 bits are a
setup (or hold in case of deactivate) time expressed in cycles. So this
should not be needed to fulfill any setup/hold timings.

Signed-off-by: Thommy Jakobsson <thommyj@gmail.com>
Reviewed-by: Naga Sureshkumar Relli <naga.sureshkumar.relli@xilinx.com>
Link: https://lore.kernel.org/r/20200224162643.29102-1-thommyj@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/spi/spi-zynqmp-gqspi.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/drivers/spi/spi-zynqmp-gqspi.c b/drivers/spi/spi-zynqmp-gqspi.c
index f23f36ebaf3dc..bd3945a5660a5 100644
--- a/drivers/spi/spi-zynqmp-gqspi.c
+++ b/drivers/spi/spi-zynqmp-gqspi.c
@@ -414,9 +414,6 @@ static void zynqmp_qspi_chipselect(struct spi_device *qspi, bool is_high)
 
 	zynqmp_gqspi_write(xqspi, GQSPI_GEN_FIFO_OFST, genfifoentry);
 
-	/* Dummy generic FIFO entry */
-	zynqmp_gqspi_write(xqspi, GQSPI_GEN_FIFO_OFST, 0x0);
-
 	/* Manually start the generic FIFO command */
 	zynqmp_gqspi_write(xqspi, GQSPI_CONFIG_OFST,
 			zynqmp_gqspi_read(xqspi, GQSPI_CONFIG_OFST) |
-- 
2.20.1

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2020-03-16  2:35 [PATCH AUTOSEL 4.4 1/7] spi: qup: call spi_qup_pm_resume_runtime before suspending Sasha Levin
2020-03-16  2:35 ` [PATCH AUTOSEL 4.4 4/7] spi/zynqmp: remove entry that causes a cs glitch Sasha Levin

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